Health & Science

How artificial sweeteners make you fat

Rats fed a steady diet of sugar substitutes were hungrier and gained more weight than rats that ate sugary food, a new study has found. The study may explain why people who drink a lot of diet soda have higher rates of obesity, diabetes, and other metabolic problems. Purdue University researchers fed sugar-filled and sugar-free yogurt to groups of rats, and found that rats that got accustomed to artificially sweetened meals were still hungry afterward and went back for more food. Why? It appears that artificial sweeteners confuse the body, which is programmed to associate sweet tastes with calories consumed; when we repeatedly eat something sweet that provides little or no calories, researchers say, we break that connection, and our confused bodies keep seeking more food. Also, the rats that frequently ate sugar substitutes also didn’t have the metabolic increase that usually follows eating a meal, so they burned fewer calories, researcher Susan Swithers tells HealthDay. Combine a larger appetite with a slower metabolism and you have a formula for severe weight gain. “The take-home message,’’ Swithers says, “is that consumption of artificially sweetened products may interfere with an automatic process.”

What’s in a kiss? Plenty

Subscribe to The Week

Escape your echo chamber. Get the facts behind the news, plus analysis from multiple perspectives.

SUBSCRIBE & SAVE

Sign up for The Week's Free Newsletters

From our morning news briefing to a weekly Good News Newsletter, get the best of The Week delivered directly to your inbox.

From our morning news briefing to a weekly Good News Newsletter, get the best of The Week delivered directly to your inbox.

Sign up

More than 90 percent of the world’s cultures engage in mouth-to-mouth kissing. But if you give it some thought, kissing seems a little silly. The mouth is the organ we use for eating, speaking, and burping, and it’s full of nasty germs and sharp teeth. So why would anyone want to put this icky aperture in contact with anyone else’s? That was the puzzle Albright College psychologist Susan Hughes explored in a study of more than 1,000 college students. She found that people use kissing to assess potential mates and to deepen or renew their bonds with those they have chosen. Men, the study found, tend to prefer sloppy, open-mouthed kisses that indicate uncontrolled passion. “Men tend to think kissing should lead to sex no matter what,” she says. Women, on the other hand, use kissing as a way of assessing men’s worthiness through biochemical signals and hints about his emotional makeup. “She’s getting a lot of information from that first kiss,’’ Hughes said. “If he’s a bad kisser, then she’s not going to want to have sex with him. No wonder we’re nervous about our first kiss.’’

The addictive power of cigarettes

Teenagers can become addicted to nicotine by smoking a single cigarette, a tobacco researcher has found. By studying adolescents who smoke only occasionally, Dr. Joseph DiFranza examined how nicotine produces dependency. He concluded that for many teens, even one exposure to cigarettes sets up a powerful reward system in the brain. Teenagers in the study who smoked as few as three cigarettes per week could not do without these occasional smokes without feeling strong cravings and irritability. As a result, they kept smoking, if even only occasionally. “Most of these self-described ‘social smokers’ were addicted to tobacco,” he says. For those who smoked more often, of course, the cravings were more urgent. “It’s a huge mistake to start smoking,” DiFranza says. “If [teens] never start, they’ll never have to worry about quitting.”

Make your own energy

It’s the latest in power walking: A new device turns the energy we exert while strolling down the street into electricity. Researchers working at several universities in the U.S. and Canada looked for ways to harness energy from the body, and realized that the knee is the most efficient place. They came up with the Biomechanical Energy Harvester, which has a tiny computer and a generator that is engaged when we decelerate our legs after we kick out to take a step. “A similar process is used in hybrid cars to make electricity when you press the brakes,” researcher Max Donelon tells Science. “It’s called generative braking.” Using their specially equipped knee brace, Donelon and his team were able to generate an impressive amount of clean energy—in just a minute, volunteer walkers generated an average of 5 watts of power, enough to recharge 10 cell phones. When fully developed, the device—now just a prototype—could be used to power a GPS locator, BlackBerrys, motorized prosthetic joints, or other portable electronic devices.

Retail therapy is a bad idea

Next time you’re feeling blue, try to avoid the mall. A new study of consumer psychology has found that people who are feeling down and withdrawn are more likely to make big purchase decisions that they’ll regret. In the study, subjects who were feeling gloomy were willing to pay up to 300 percent more for the same item as people on an even emotional keel. Researchers said that sadness and self-focus make people devalue themselves and their current possessions; they literally feel worthless. So when given the chance, they’re willing to spend foolish amounts of money for new material goods, as a way of enhancing their “worth.’’ The problem is that the boost they get is very short-lived, and buyer’s remorse sets in soon afterward. Researcher Cynthia Cryder of Carnegie Mellon University said the best defense against foolish shopping sprees “is being aware that you’re sad in the first place.’’ That’s not as easy as it sounds: Most people, Cryder says, “have no idea that their feelings influence their [buying] decisions.’’